Nu-nitro substituted, nitro containing polyurethanes



Patented Apr. 12, 1966 3,245,962 N-NITRO SUBSTITUTED, NITRO CONTAINING POLYURETHANES James R. Fischer, Claremont, Califi, assignor to Aeroietgfilelal Corporation, Azusa, Califi, a corporation of N0 Drawing. Filed Apr. 22, 1963, Ser. No. 275,474 20 Claims. (Cl. 260-775) This invention relates to high molecular weight polyurethane polymers containing nitro groups.

This application is a continuation-impart of applicants copending US. application, Serial. No. 87,710, filed February 7, 1961, now US. Patent 3,087,061.

The principal object of this invention is to prepare high energy high molecular weight compounds useful as solid smokeless propellants. The nitro-substituted polyurethanes of my invention are high energy solid propellants and can be used as a primary propulsion source in rocket propelled vehicles and can also be used as a propellant for artillery missiles. When used as the primary propulsion source for rocket vehicles, they can be conveniently ignited by a conventional igniter such as, for example, the igniter disclosed in assignees copending United States patent application, Serial No. 306,030, filed August 23, 1952, now US. Patent No. 3,000,312. The propellant is preferably cast in place in tubular form and restricted in the conventional manner with a relatively inert resin such as a nonnitrated polyurethane foam or a polyester resin inside a chamber having one end open and leading into a conventional venturi rocket nozzle. Upon ignition, large quantities of gases are produced and exhausted through the nozzle, creating propulsive force.

The polyurethanes of my invention possess numerous advantages over the composite and double-base solid propellants commonly in use today. In the propellant substances of my invention, the oxidizer is an integrated part of the chemical compound, thereby enhancing the reproducibility of ballistic properties and eliminating dangerous and costly grinding and mixing operations. In propellant compositions commonly in use at present, the oxidizing element is usually a finely divided inorganic oxidizing salt which is dispersed in some type of combustible organic binder, usually an organic resin. Numerous problems are involved in the preparation of this type of propellant; namely, obtaining uniform dispersion of the oxidizing agent throughout the binding composition and at the same time preventing the formation of cracks and faults in the propellant grain itself.

Although it is desirable to avoid the need for incorporating additional oxidizer, additional oxidizer can, if desired, be added to the novel resins of my invention.

Any solid inorganic oxidizing salt such as ammonium perchlorate, ammonium nitrate, or the like, can be used for this purpose in a conventional manner. For example, the method disclosed in assignees US. patent application, Serial No. 829,180, filed July 20, 1959, can be used by merely substituting the high energy resins of this invention for the fuel binder materials disclosed therein.

The polyurethanes of my invention, having no metals whatsoever present, are smokeless and, since all the elements of the propellant are integrated in the molecular chain itself, there are no difliculties encountered in dispersing the oxidizing component nor is it necessary to perform any difiicult and dangerous grinding and mixing operations.

Thehigh specific impulse and high density of the polyurethane compositions of my invention render them extremely valuable wherever weight and size considerations of the propellant charge are important.

In addition to these valuable propellant properties, it has also been found that my materials possess high temperature and impact stability, thereby rendering their production both safe and economical.

The polyurethanes of my invention are conveniently prepared by post-nitrating the polyurethanes disclosed in applicants copending US. application, Serial No. 87,710, filed February 7, 1961. In this manner, additional nitro groups are incorporated into the polyurethanes disclosed in application, Serial No. 87,710, thereby creating a product with a higher nitro content and thus higher energy.

The polyurethanes to be post-nitrated are conveniently prepared by reacting a diisocyanate with a diol, in accordance with the general reaction scheme set forth in US. patent application, Serial No. 87,710 shown below:

y(HOR-OH) y(OCN-R--NCO) 0 H H I 0 I [C"II IR1 I- JO-RO-] wherein R is a lower alkylene, nitroalkylene, nitraz-aalkylene, or nitrazanitroalkylene radical; R is a lower alkylene, nitroalkylene, nitrazaalkylene, nitrazanitroalkylene, dialkoxynitroalkylene, or dialkyloxamide radical and y is a whole number greater than one, the number of repeating units in the polymer chain. It will be appreciated that in any given batch of propellant, individual molecules may vary in length from several to tens of thousands of repeating units, hence, molecular weight figures represent statistical averages. The exact nature of terminal groupings is not known and will vary depending upon whether plasticizers, polymerization agents, etc. are present. Moreover, a given molecule may even form a ring and thus leave no dangling radicals.

It has been found that the reaction time may be shortened and higher molecular weight polymers obtained, for example, polyurethanes having molecular weights of the order of about 75,000, by conducting the reaction in solution in the presence of a suitable catalyst. Any of the conventional catalysts used in the preparation of polyurethane resins can be used; however, several catalysts have been found particularly useful, among which are boron trichloride; boron trifiuoride complexes, such as boron trifluoride etherate; and metal chelates, such as ferric acetylacetonate. Suitable solvents are 1,4-dioxan, N,N-dimethylformamide, butyrolacetone, acetone, etc. where catalysts are employed, they can be used in quantities within the range from more traces up to amounts equivalent to about 1 percent by weight of the total mass or even higher. The use of catalysts is not critical; however, for economic reasons it is usually preferable to use them.

The polyurethane starting compounds can comprise either linear polymers or cross-linked polymers. The linear polymers are those formed from appropriate isocyanates and alcohols without the addition of any cross linking agent. That is, they are merely linear chains composed of alternate isocyanate and alcohol monomers. The cross-linked polymers, on the other hand, are prepared by employing a cross-linking agent in addition to the isocyanate and alcohol monomers which acts as a bridge between the linear isocyanate-alcohol polymers, thus bonding these polymers together. Any suitable cross-linking agent such as polyisocyanates, triols, glycerol, trimethylol propane, tris (hydroxymethyl)nitromethane, etc., can be used.

The polyurethane polymerization reaction can be effectively carried out at any temperature, the only effect of temperature variation being a corresponding change in the rate of reaction. The polymerization can be conducted at room temperature although higher temperatures increase the rate of reaction and might be dea sirable in certain cases. However, the polymerization will also take place at temperatures much below room temperature and thus temperature is not a critical variable.

It is evident from the reaction scheme set forth above that a wide variety of polyurethane starting compounds can be prepared simply by varying the particular alcohol and isocyanate used in the reaction. Examples of diols which may be used are dialkoxynitrazaalkylene diols having the general formula:

ITIO: '1 T HO A A LI\ A J 0 0 wherein A and A are the same or different and are lower alkylene radicals and x is a whole number from 1 to 6, inclusive, and dihydroxyalkyloxamides having the general formula N HOA-NHC-CNH-AOH wherein A" and A are the same or different and are lower alkylene radicals. Specific examples of diols are:

N,N-bis Z-hydroxyethyl oxamide;

N,N'-bis (3 -hydroxypropyl) oxamide;

N,N'-bis -hydroxymethyl oxamide;

N,N'-bis 6-hydroxyhexyl) oxamide;

N,N-bis Z-hydroxypropyl oxamide;

N Z-hydroxyethyl N- 3 -hydroxypropyl) oxamide;

2,2-dinitrol ,3 -propanediol;

1,3-propanediol;

Z-nitro-Z-ethyl-l ,3 -propanediol;

3 ,3 -dinitro-1,5-pentanediol;

2,2,4,4-tetranitro-1,5-pentanediol;

,5 ,5 -trinitrol ,Z-pentanediol;

2-nitro-2-methyll ,3 -propanediol;

4,4,6,8,8-pentanitro-1,1l-undecanediol;

4,4,6,6, 8, S-hexanitrol ,1 l-undecanediol;

Ethylene glycol;

5 ,5 -dinitrol ,Z-hexanediol;

3 -nitraza-1,S-pentanediol;

2-nitro-2-bromol 3 -propanediol;

1,4-butanediol;

2-nitro-2-chlo ro- 1 ,3 -propanediol;

3 ,6-dinitraza-1, 8-octanediol;

2-butyne-1,4-diol;

5 -nitro-5 -aza-3 ,7-dioxa-1,9-nonanediol;

5 ,7-dinitro-5 ,7-diaza-3 ,9-dioxa-1,1l-undecanediol;

5 ,7,9-trinitro-5 ,7 ,9triaza-3 1 l-dioxa- 1 13-tridecanedio1;

5,7,9,1l-tetranitro-5,7,9,l l-tetraza-S,13-dioxa-1,15-

pentadecanediol;

5,7,9,l1,13 -pentanitro-5,7,9,11,13-pentaza-3,12-dioxa- 1,17-heptadecanediol;

6-nitro-6-aza-4,8-dioxa-1,1 l-undecanediol;

6,8-dinitro-6,8-diaza-4,10-dioxa-1,l3-tridecanediol;

6-nitro-6-aza-3 ,9-dioxa-1,1l-undecanediol;

6, 8-dinitro-6, 8-diaza-3, 1 l-dioxa- 1 l 3-tridecanediolg 7 -nitro-7 -aza-4, 1 O-dioxa-l l 3 -tridecanediol;

9-nitro-9-aza-7,l l-dioxa-l ,l7-heptadecanedio1;

5 ,9-dinitro-5 ,9-diaza-3 ,1 l-dioxa-l ,13 -tridecanediol;

6,l2dinitro-6,12-diaza-3 -dioxal l7-heptadecanediol;

and

5,7,9,11,13-pentanitro-5,7,9,11,13-pentaza-3,l6-dioxa- 1,18-octadecanediol.

Examples of isocyanates which may be used are:

Lower alkylene diisocyanates such as- Methylene diisocyanate, Ethylene diisocyanate, and 1,3-propane diisocyanate, Hexamethyiene diisocyanate;

Nitroalkylene diisocyanates such as- 3,3-dinitro-l,5-pentane diisocyanate 3,3,5 ,7 ,7-pentanitro-L9-nonane diisocyanate, 2,2,4,4-tetranitro-l,S-pentane diisocyanate, and 5,5,5-trinitro-1,Z-pentane diisocyanate;

Nitrazaalkylene diisocyanates such as 2,5 -dinitraza- 1 ,6-hexane diisocyanate, 3,6-dinitraza-l,8-octane diisocyanate, 3-nitraza-1,5-pentane diisocyanate, and 2-nitraza-1,4-pentane diisocyanate; and

Nitrazanitroalkylene diisocyanates such as- 5 -aza-3,3,5 ,7,7-pentanitro-1,9-nonane diisocyanate, 6-aza-3,6-dinitro-1,8-octane diisocyanate; and 5-aza-3,3,5-trinitro-1,9-nonane diisocyanate.

Any of the above-named alcohols and isocyanates and mixtures thereof can be polymerized to form starting compounds of this invention.

The post-nitration procedure of this invention proceeds in accordance with the following general reaction scheme:

wherein y, R and R have the meaning previously set forth in the specification.

Two procedures may be used to accomplish the postnitration as follows:

Procedure A.--The polyurethane polymer starting compound is dissolved in an excess of percent nitric acid at a temperature of about -40 C. to about 65 C. 0 C. is prefered since it is easiest to maintain. The solution is immediately precipitated by pouring the acid solution into cold water, preferably ice-water. The postnitrated polyurethanes of the invention may then be washed free of acid with any suitable washing agent such as water, recovered by any of the common liquid-solid separation means, such as filtration, decantation or centrifugation, and then dried.

Procedure B.The polyurethane polymer starting compound is dissolved in an excess of 100 percent nitric acid at about 40 C. to about 65 C. 0 C. is preferred since it is easiest to maintain. The acid is then removed by distillation and the residue is dissolved in a solvent for the polymer. Polar solvents, particularly ketonic solvents, such as dioxan, methyl ethyl ketone, and acetone are preferred. The polymer is immediately precipitated from solution by adding a diluent which will dissolve nitric acid and the polymer solvent but in which the polymer will precipitate. Suitable diluents include, chlorinated diluents and hydrocarbon diluents such as, chloroform, methylene chloride, carbon tetrachloride, pentane and hexane. In this manner any nitric acid which remains bound in the polymer is removed. The polymer may then again be washed with a suitable diluent, recovered by any of the common liquid-solid separation means, such as filtration, decantation or centrifugation, and then dried. Procedure B is substantially anhydrous and is preferred when polymers which are sensitive to degradation by hydrolysis are being treated.

The nitration step of either Procedure A or Procedure B may take place in the presence of a water scavenger such as, sulfuric acid, phosphoric acid, boron trifluoride, acetic anhydride or trifluoroacetic anhydride if anhydrous nitric acid is unavailable. Best results are obtained, how ever, when 100 percent nitric acid is used alone.

Each step of the above disclosed processes is preferably carried out with agitation. The use of agitation is not critical, but a more even reaction rate is obtained. The pressure under which each step of the above-defined processes may be conducted is preferably atmospheric. Pressure, however, is not critical and increased pressure up to about 500 atmospheres may be employed if desired.

To more clearly illustrate the invention, the following examples are presented. It should be understood that these examples serve merely as a means of illustrating and the precipitated post-nitrated polyurethane polymer the invention and should not be construed as limiting the having the formula: invention to the particular embodiments and conditions N01 0 set forth therein. Parts and percentages are by weight .6 F g O j unless otherwise mdlcated. 5 1 NO I N 02 Example I 5 was washed free of acid and dried. Yield, 6.6 g. which was 918 percent of theory.

30 g. of the polyurethane prepared from stoichiometric Analysis calculated f CBHIZINGOIZ. proportions of 3,3-dinitro-lg5 pentane diisocyanate and V N,N-bis(Z-hydrmryethylloxamide was added to 600 ml. Carbon Hydrogen, Nitrogen. m of of 100 percent n1tr1c-ac1d. The solutlon obtamed was p rcent percent percent comblustion, maintained at 6065 C. for one hour. The solution vcL/g' was cooled to 251C. and poured 1nto 10 hters of 1ce- Calculated 2128 M5 21121 2,711 water. The prec1p1tated post-nltrated polyurethane poly- Found 27.78 3.05 21. 37 2, 71s

mer having the formula:

was washed free of acid and dried. The yield was 41.5 g. Example 11/ which was 96.5 percent of theory.

Analysisi calculated for CBHmNmOm: The polyurethane prepared from stolchlometnc propontions of 3,3-dinitro-1,5-pe11t ane diisocyanate and 2- Q ni-tro-2-methyl-1,3-propanediol was dissolved in 100% $3222? 332253 1 3853? gg ff gg nitric acid and recovered in accordance with procedure A calJg. shown prevlously. The post-mtrated polyurethane poly- I mer having the formula: Calculated 20. 01 2.69 23.33 2, 561 0 0 f CH3 Found 26.26 2.78 23.58 2,531 5 y I 1 I [-CIIICHzCHz-?CH2CH2NCO-GH3C-CHz-O], Example II N02 N02 N02 NO:

4.0 g. of the polyurethane prepared from stoichiometric was recovered The i l was 9 of theory-W proportions of 3,3-dinitro-1,5-pentane diisocyanate and 5 2,2 -d1n1tro-1 ,3-propaned1ol was added to 40 ml. of 1 00 S5 3? gg g? ggg f ggf gg percent n1tr1c acid malntained at 0 C. Afterstanding my;

for 30 minutes at 0 C., the nitric acid solution of the v polymer was poured into one liter of ice-water. The Calculated 28.15 3.22 20;90 2,871

coagulated product was filtered, washed with a five per- 40 Found 28'75 21856 cent solution of sodium bicarbonate; followed by distilled water and then vacuum dried to a constant weight. The Example V post-flitlated Polyurethane Polymer having the formlllai The polyurethane prepared from stoichiometric pro- 0 NO; 0 N-o, portions of 3-,3-dinitro-1,5-pentane diisocyanate and 2,2,4,

g g 4-tetranitro-1,5-pentanedio1 was dissolved in 100% nitric acid and recovered in accordance with procedure A shown N02 N 2 N 1 N previously. The post-nitrated polyurethane polymer havweighed 4.8 g. which was 98 percent of theory. ing the formula:

- fl) 5N0; (1? N02 N 02 [-CIIICHPCH2(IICH2-CHr-ITL-COCH2-CCH2C-CH2O] N 02 N 02 N 02 N02 N02 Analysis.Calculated for C H N O was recovered. The yield was 98% of theory.

Heat of combustion: Cal/g. o b H dr N t H t r pethegl ti gerc ilz p :l1 l com ils ion, Calculated 2260 'Found 23 05 0 l l t d 24. 01 2. 42 22. 40 2,320 F u l l di? 23.77 2. 59 21.63 2,320 Epxample The polyurethane prepared from stoichiometric pro- Example 111 portions of 3,3-dinitro-l,5-pentane diisocyanate and 4,4,6, A soh'ltiofi f 52 f a polyurethane r p fr 8,8-pentanitro-1,11-undecanediol was dissolved in 100% stoichiometric proportions of 3,3-dinitro-1,S-pentane dinltflc Q d and recovered in accordance With Procedure A isocyanate and ethylene glycol in 55 ml. of 100 percent own previ u ly. The post-ni rated polyurethane polynitric acid was maintained at 0 C. for thirty minutes. mer having the formula: I

The-acid solution was-poured intoone' liter of ice-water was recovered. The yield was 97% of theory... x

Carbon, Hydrogen, Nitrogen, Heat of Carbon, Hydrogen, Nitrogen, Heat 01 percent percent percent combustion, percent percent percent combustion,

caL/g. calJg.

Calculated 28.92 3.37 20. 02 3,075 5 Calculated 28.79 3.35 20.60 3, 000 Found 29. 37 3. 41 20. 92 3, 015 Found 28.83 3. 45 21. 37 2, 996

Exam le VII p Example X The polyurethane prepared from stoichiornetric proportions of 3,3-dinitro-l,5-pentane diisocyanate and 4,4,6,6, 8,8-hexanitro-l,1l-undecanediol was dissolved in 100% Portions of 3,6'dinitl'aza'lrsfioctane diisocyallate and nitric acid and recovered in accordance with procedure A ,N" (2' y Y y ll was dissolved n 100% shown previously. The post-nitrated polyurethane poly.- nitric fe a d recovered in a co da h Procedure mer having the formula; A shown previously. The post-nitrated polyurethane The polyurethane prepared from stoichiometric pro- E I? 0 a (lil) III 0 g N 0 g 171' O z [-C-N-C Hr-C Hg-CC Hr-CHx-III-C-O-CHz-C Hg-C HrC"-QH2'CCHrC-CHzCHgCHgO-] N02 N02 N01 N02 N08 N02 was recovered. The yield was 97 of theory. polymer having the formula:

i i n l? i [C NCH C H;NC n on m-oHr-c H=I -I-c- .-.o.- -o r-G firN.-C fen-cure H -O],

N O 2 N O a N 0 2 N O 1 was recovered.

Carbon, Hydrogen, Nitrogen, Heat of t r percent percent pement s Carbon, Hydrogen, Nitrogen, Heat of 559 percent percent percent combustion, eaL/g.

Calculated 27. 28 8. 05 21. 21 2, 858 l M Fmmd- 85 12 79 823 Calculated 20. 09 I 3. 13 2e. 00 2, 773 v V p Found 20. 41 3. 23 25. 44 2, 700

Example VIII Example X I The polyurethane prepared from stoichiometric proportions of 3,3,5,7,7-pentanitro-1,9-nonane diisocyana-te The polyurethane prepared from stoichiornetric proand 2,2-rdinitro-1,3-propanediol was dissolved in 1.00% portions of 3,6-dinitraza-L8-octane diisocyanate and'ethnitric acid and recovered in accordance with procedure ylene glycol was dissolved in 100% nitric acid and re- A shown previously. The post-nitrated polyurethane covered in accordance with procedure A shown prepolyrner having the formula: 40 viously. The post-nitrated polyurethane polymer having (a NO: 1 10; (6 NO: -'N".-CHrrCHrCfCHrCH-fCHrCCHrOHrN-1-C1-0CH7'$CH -O] N0: N0: N0: N0: N0: N01

was recovered. The yield was 93% of theory. the formula:

ii i i u -ITI-CHaCHr-NrCHrCH:NCH:-CH2lTIC-OCH2CH:-O],

was recovered.

Carbon, Hydrogen, Nitrogen, Heat oi percent percent percent combustion,

caL/g.

Calculated 24.32 2.48 22. 20 2,420 Found 24.39 2.39 22.02 2, Carbon, Hydrogen, Nitrogen, Heat oi percent percent percent comblulstion, C9- g.

Example IX a Calculated 27.28 2. 66 25.45 3,008 The p ly r a e pr pa d fromustmchwmetrw p Found 26.63 3 portions of 3,3-d1n1tr0-1,5-pen-tane dusocyanate and 5, 5- clinitro-LZ-hexanediol was dissolved in 100% n1tr1c acid and recovered in accordance with procedure A shown previously. The post-nitrated polyurethane polymer having the formula:

0 -u 1 ii 7 Example XII -o o C-CH on N-c-o-cn CH-O- NO m l Hr r 2 The polyurethane prepared from-stqrchiometnc pro- N02 N01 N01 CHTCH1 C CH' portions of 3,6-dinitraza-1,8-octane diiso'cyanate and 5,5-

o, dinitro-LZ-hexanediol was dissolved in 100% nitric acid was recovered. and recovered in accordance with procedure A shown previously. The post-nitrated polyurethane polymer havand recovered in accordance with procedure B shown ing the formula: previously. The post-nitrated polyurethane polymer havr r i [--N0Hs-cHs-N-CHsoHsNcHs0Hs-1Fc0-oH-oHs0- NO: N O: CH: N02

CHz-(f-CH;

N O: was recovered. ing the formula:

ii i n [CNCH2CH2-N-CHaCH2NCOCHzCH-O] N0,

N02 N02 CHrCH-CHz-C-Cfl'a N02 NO: was recovered.

Carbon, Hydrogen, Nitrogen, Heat of percent percent percent comblulstion,-

Ca g.

Carbon, Hydrogen, Nitrogen, Heat of percent percent percent combustion, Calculated 28. 67 3. 78 23. 89 3, 147 caL/g. Found 28. 8S 3. 87 24. 15 3, 148

Calculated 28.92 3. 64 22. 49 3,054 E l X111 Found 27. 48 3. 59 21.16 3,067

The polyurethane prepared from stoichiometric proportions of 3,6-dinitraza-'1,8-octane diisocyana-te and 2,2-

dinitro-1,3propaned-iol was dissolved in100% nitric acid Having fully described the compounds. their method of and recovered in accordance with procedure B shown Preparation and their t t es, it is desired that the inpreviously. The post-nitrated polyurethane polymer vention be limited only within the lawful scope of the having the formula: appended claims. I

No, No, 0 NO: l( J NCHg-CHfl 1 C FQH2I I CHPCHrN O OH2 -CH2 O]y N0! 1 :0: tho,

was recovered. I claim:

1. As compositions of matter, the nitro polyurethanes containing the structural unit:

40 Carbon, Hydrogen, Nitrogen, Heat of percent percent percent combustion, I] H calJg. [-CNRN00R'--o--] 23 60 2 65 24 5s 2 379 N02 23110 2172 23:15 21377 wherein R is a radical selected from the group consisting of lower alkylcne, nitroalkylene, nitrazaalkylene, and ni- I trazanitroalkylene radicals, R is a radical selected from the group consisting of lower alkylene, nitroalkylene, Example XIV nitrazaalkylene, nitrazanitroalkylene ,dialkoxynitroalkyl- The Polyurethane P p m stolchlometflc P ene and dialkyloxamide radicals and y is whole number portions of 3-nitraZa-LS-pentane d-ilsocyanate and ethylgreater th one glycol was dissolved in 100% nitric acid and recov- 2. As a composition of matter, the nitro substituted ered in accordance with procedure B shown previously. polyurethane containing the structural unit:

if i i r [--CIIICH CHr-(f-CHr-CHg-N-C-O-OHz-CHreNOCNCH -CH -O-l,

N 02 .NO: N 02 N 02 The post-nitrated polyurethane polymer having the fOT'. wherein y is a whole number greater than one. mula: 3. As a composition of matter, the nitro substituted N02 0 polyurethane containing .the structural unit: II I II c CH CH N-CH CH NCOCH CH 0- f 2- r" 2- z- I z I- ]y N O, o N 2 Nos N02 H II [-C-N-OHrCHrC-CHr-CHrNCO-CHzC-CHg0-] was recovered.

N05 N03 N 02 N 01 Carbon, Hydrogen, Nitrogen, Heat of 1 percent percent percent oombu/stion, wherem y is a whole number greater than one.

4. As a compositionyof matter the nitro substituted 4 polyurethane containing the structural unit: Calculated 27.28 3.43 23.86 2,843 Found 2e. 41 3. 5 23. 40 2,832

ii 7 1 Example XV [-CITT-CHz-OHr-CCH CH:IIICO-CHT-CHrO], The polyurethane prepared from sto-i'chiornetric pro- NO: NO: NO:

port-ions of S-nitraza-LS-pentane diisocyanate and 5,5- dinitro-1,2-hexane-diol was dissolved in 100% nitric acid wherein y is a whole number greater than one.

1 1 l 2 5. As a composition of matter, the nitro substituted 13. The process of claim 12 which comprises dissolving polyurethane containing the structural unit: the polyurethane polymer in nitric acid at a temperature of C. i i 1 El 14. The process of claim 11 which comprises dissolving the polyurethane polymer in an excess of 100 percent nitric N-CH CH C-CH CH NCO H 0-011 0- l r r F C acid at a temperature of about 40 C. to about 65 C., N01 removing the acid by distillation, dissolving the polymer residue in a solvent and immediately precipitating the wherein is a Whole number greater than one. polymer in a diluent, which will dissolve nitric acid and the 6. As a composition of matter, the nitro substituted polymer solvent but in which the polymer will precipitate, polyurethane containing the structural unit: and separating the polymer thus produced.

it i i 1i T [C-NCHr-CHz-C-CHz-CH-CHz-CCH2-CH2NC-OQH2-?CHzO-b N02 N02 NO: NO: N02 N02 wherein y is a whole number greater than one. 15. The process of claim 14 which comprises dissolving 7. As a composition of matter, the nitro substituted the polyurethane polymer in nitric acid at a temperature polyurethane containing the structural unit: of 0 C.

1| i i ll [C-IIICHzCHz-NCHzCHz-N-CHr-C HzlFl-CO-CHCH2+0] N02 N02 CH2 NO:

CHz(?-CH3 N02 wherein y is a Whole number greater than one. 16. The method of preparing nitro-substituted poly- 8. As a composition of matter, the nitro substituted urethane polymers which vcomprises treating a polyurepolyurethane containing the structural unit: thane polymer with nitric acid said polymer being pre- 0 pared 1iffy condensing a diisgciyanatel lciompostion selected H l H rom t e grou consisting o ower a ylene iisocyanates, [O IITCHrCHrN CHFCHT-NC*O CHFCHPO nitroalkylene ciiisocyanates, nitrazaalkylene diisocyanates, N01 N01 nitrazonitroalkylene diisocyanates, and mixtures thereof wherein y is a whole number greater than with a diol composition selected from the group consisting 9. As a composition of matter, the nitro substituted 0f lQW alkylene (H015, nitI'0anY1e11e (H015, l y polyurethane containing th t u l i ene diols, nitrazanitroalkylene diols, dialkoxymtrazaalkylene diols, dihydroxyalkyloxamides and mixtures thereof. 17. The method of claim 16 which comprises dissolving the polyurethane polymer in an excess of 100 percent wherein y is a whole number greater than one.

10. As a composition of matter, the nitro substituted polyurethane containing the structural unit:

wherein y is a whole number greater than one. nitric acid at a temperature of from about -40 C. to 11. The method of preparing nitro-substituted polyabout 65 C-, immediatfilvy pf p g the p lym r by urethane polymers which comprises treating a polyurepouring the polymer solution into cold water and recoverthane with nitric acid said polyurethane having the foring the polymer.

18. The process of claim 17 which comprises dissolving mula:

0 O the polyurethane polymer in nitric acid at a temperature l| ll I of 0 C, [fiCIiIR -I]\I- GO R 19. The process of claim16 which comprises dissolving H H the polyurethane polymer in an excess of 100 percent wherein R is a radical selected from the group consisting nitric id at a temperature of about -.40 C. to about lower alkylene, nitI- Oa1ky1ene nitrazaalkylenev and 65 C., removing the acid by distillation, dissolving the mtrazanitroalkylene radicals, R is a radical selected olymer residue in asolvent and immediately precipitating from the group consisting of lower alkylene, nitroalkylene, the polymer in a diluent which will dissolve nitric acid nitrazaalkylene, nitrazanitroalkylene, dialkoxynitroalkyland the polymer Solvent but in which the polymer will t g gg i igggzii radicals and y is a Whole precipitate, and recovering the polymer thus produced.

12. The method of claim 11 which comprises disth i 2 2 f Clalm. 19 l i (igmpnses dlssolvmg solving the polyurethane polymer in an excess of e E yur'e ane p0 ymsr m mtnc at a temperature percent nitric acid at a temperature of from about 40 of 0 C. to about 65 C., immediately precipitating the polymer No references cited by pouring the polymer solution into cold water and recovering the polymer. LEON BERCOVITZ, Primary Examiner. 

1. AS COMPOSITIONS OF MATTER, THE NITRO POLYURETHANES CONTAINING THE STRUCTURAL UNIT: 